Treatment of naphthene base oil



Nov. 12, 1940. c. T. ANN ETAL TREATMENT OF NAPHTHENE BASE OIL Filed Aug.25; 1958 N Y .www im n Mmm L@ 3mm 02m mmmwf, n Hmmlu/ A CHL R w M/Um B T+I UNITED STATES oFFicE TREATMENT OF NAPHTHENE BASE OL Charles T. Ann,Herman I. Wilson, and William C. Patterson, Port Arthur, Tex., assignorsto The Texas Company, New York, N. Yi, a corporation of DelawareApplication August 25, 1938, lSerial No. 226,630

11 claims. (o1. 19e- 34) This invention relates to the treatment of theundesired asphaltic and tarry bodies, all, or naphthene base oil. Itparticularly concerns the substantially all, of thoseconstituentspresent in treatment of lubricating oil stocks derived from the oil andAwhich impart to the oil a desirable naphthene base crude petroleum forthe producgreen cast. Vacuum distillation over caustic also tion oflubricating oils substantially free from destroys this green cast.Thepurpose of distilling asphaltic and organic acidic constituents buthavover caustic is to remove the naphthenic acids in ingia desirablegreen cast or bloom. the form of a soap which remains .behind in the Theinvention broadly contemplates treatment still as a residue. Thedesirable'green colorof fractions derived from naphthene base crudeforming vconstituents apparently remain in this by a process involvingdeasphalting in the' presresidue and consequently are not' present inthe10 ence of a liqueed normally gaseous petroleum distillate lubricatingoil fractions. Y hydrocarbon solvent and treatment of these frac- From apraCtiCai StaldDOint it iS imPOSSible t0 tions with alkali in thepresenceof the liquefied effect removal of the naphthenic acids from thesolvent for the purpose of separating therefrom oil by simply Washingwith caustic soda solution,

15 the naturally occurring organic acid-constitudue to the extremereadiness with which emul- 15 ents. o o sions are formed and the extremedifficulty en- The process of this invention is particularly counteredin breaking .these emulsions. Distillaadapted to the preparation oflubricating oilhavtion of the oil over caustic, does not give rise toing a desirable green cast and substantially free emulsion diicultiesbutfor some reason or from asphaltic and acidic constituents fromlubriother, as indicated above, the resulting distillates 20 eating oilstocks derived from naphthene base khave a bluish cast instead of thedesired green crudes and. particularly the residual fractions of cast.such crudes. y It has been discovered that naphthenic acids l Theprocess is also applicable,4 to the treatment can bek removedv from thisoil by treatment With of heavy residual fractions of naphthene baseValkali in the presence Of a dilnenty SllCh aS PI'O- 25 crudes rich innaphthenic acids such as the still pane, WthOut encountering particulardifficulty 1 bottoms produced in the vacuum distillation over withrespect t0 the formatiOn OfemlliSiOnS- BY caustic of lubricating oilfractions derived from carrying Out the treatment Under Certain speci-Gulf Coastal crude. These bottoms are treated ed conditions, as will beexplained mere'fully, with acid in order to liberate a fractioncomprisit is possible to substantially avoid the formation 30 ing crudenaphthenic acids. This crude fraction 0f emulsions which are diliicultto break.I Prois treated with propane to precipitate asphaltic panedeasphalting, Geupled With treatment with and tarry matter. Followingthis, the naphthenic the alkali, pIOdllCeS a DI'OduCt 0f Superior ChaI-acid material, while still diluted with propane, is acteristics and also`avoids the necessity for subtreated with an alkali to saponify theacids and jecting the resulting oil stock to treatment with 35`theresulting saponied material is then separated sulphuric or otherinorganic acids as practiced from the oily constitutents. The saponiedacids in the prior art. may be subsequently treated with an inorganic Itis advantageous to employ lthe alkaline acid in order to liberate them.treatment of this invention invconjunction with It has been found thatlubricating oils of dedeasphalting 0f the Oil With a S01Vent Such as 40sirable green cast can be prepared by deasphaltpropane, because thepropane used in the deing naphthene base reduced crude and treatingasphalt-,ing step serves as a diluent in the alkali the oil, while inpropane solution, with an aquetreating Step. thus acting as a commondiluent in ous solution of caustic soda for the removal of both steps.It is-possible that the propane facilinaphthenic acids. tates theretention of the desirable color-forming 45 In the conventionaltreatment of this type of constituents in the oil during the treatmentwith reduced crude this green cast is destroyedand alkali, thuspreventing their removal in thesaoil having a blue cast or bloomresults. l ponied material, as is the oase when distilling Theconventional treatment of these lubrithe oil over caustic, as explainedabove. 5o eating oil fractions has usually involved treatment In order,to illustrate the invention further, 50 with an inorganic acid,followed by neutralizareference will now be made to the accompanyingtion. Vacuum distillation over caustic has also drawing:A been employed,or a combination such as chem- A residual naphthene base lubricatingoilstock, ical treatment and vacuum distillation. obtained by distillingthe lighter fractions from Acid treatment apparently removes, alongwith. a Gulf Coastal crude, is conducted from a source 55 not indicatedto a mixer I. Propane, conducted from a source not indicated, isintroduced to the mixer I wherein it is mixed with the lubricating oilstock in the proportion of about 8 to 12 parts of propane to 1 part byvolume of stock. The resulting mixture is conducted to a separator 2wherein it is subjected to settling at a temperature around 70 F. to 180F in order to precipitate asphaltic constituents. The thus deasphaltedsolution is advantageously conducted to a second separator 3 for theprecipitation of further asphaltic constituents of a resinous nature andwhich is effected by maintaining the mixture at a somewhat highertemperature, for example,

around F. to 200 F. If desired, an additional quantity of propane may bemixed with the l charge to the separator 3.

The completely deasphalted solution is now drawn off from the separator3 and introduced to the lower portion of a treating tower 4. This towermay beprovided with suitable packing material. Advantageously, thepacking may consist of several perforated cones 5 located in the lowerportion of the tower. These cones are for the purpose of effectingcontact and mixing between the .entering propane-oil mixture and thealkali.

Above the cones, and extending into the upper portion of the tower,grids 6 may be provided, advantageously consisting of wire screening.

Alkali, consisting of caustic soda dissolved in water, is introduced tothe upper portion of the tower as indicated. In starting up the tower itis advantageous to flll it first with the mixture of propane and oil andthen commence charging the caustic soda solution, allowing the level ofthe caustic solution to build up slowly to a desired level a shortdistance above the cones 5 and corresponding to the point indicated byliquid level indicator lI. The liquid level is maintained at this pointduring the continuous operation of the tower by drawing oif the spentcaustic continuously from the bottom of the tower as indicated. In otherwords the interface level between the caustic layer and the oil layer ismaintained relatively low in the tower. Sufficient pressure must bemaintained on the system so as to maintain the diluent in a liqueedcondition during the caustic treatment as Well as during the precedingdeasphalting treatment.

The treated oil solution is continuously withdrawn from the top of thetower through a pipe 8. Through the pipe 8 the treated solution isconducted to a settling tank '9 where any aqueous carry over may beseparated from the oil and drawn off. The settled mixture is thenconducted to a stripper I0 wherein the propane is stripped from the oil.

Where it is desired to recover the naphthenic acids from the mixturebeing drawn olf from the botton ofthe tower d, this can be accomplishedin the usual fashion by treatment with an inorganic acid so as toliberate the naphthenic acids.

The mixture of spent caustic drawn off from the bottom of the tower 4may, if desired, be introduced to a washing tower II, provided withsuitable packing material, and wherein it is washed with an additionalquantity of the liquefied hydrocarbon solvent. The spent causticsolution is introduced to the upper portion of the tower, while asolvent, such as propane, is introduced to the lower portion of thetower. The washing is thus effected on the countercurrent principle forthe purpose of removing from the spent caustic oil which may beassociated therewith.

The washed caustic material is drawn off from the bottom of the tower II while the solution of oil and propane is removed from the top of thetower and advantageously conducted to a washing tower I2, somewhatsimilar to tower II, but in which the washing agent comprises water. TheWater and sludge is withdrawn from the bottom of the tower I2, while thewashed solution of oil and propane is removed from the top of the towerand conducted to a stripper still to separate the solvent from the oil.

It is advantageous to employ a weak caustic soda solution in the tower 4so as to prevent salting out of the naphthenic acid soaps duringtreatment within the counter-current tower. The caustic soda solutionemployed advantageously consists of around 0.2% to 0.5% by weight ofcaustic soda. It its advantageous to use it in substantial excess-thatis, from 25% to 200% by volume in excess of the amount required toneutralize the organic acidity contained in the oil undergoingtreatment. While more concentrated caustic solutions may be used asshown in the subsequent example, it is usually preferable to employ itin the less concentrated form.

While caustic soda has been specifically mentioned, it is contemplatedthat other alkaline reagents may be employed, such as ammonium hydroxideor potassium hydroxide.

While in the foregoing description the alkali treatment follows thedeasphalting step, it is contemplated that instead it may precededeasphalting. If desired, the diluted oil may be subjected to alkalitreatment subsequent to the initial deasphalting step and prior to thefinal deasphalting step for removal of resinous constituents.

The following results were obtained in treating a residual lubricatingoil fraction having a viscosity of 270 Saybolt Universal seconds at 210F. and derived from Manvel crude. Two runs were made. In the first runthe resi'duum was subjected to deasphalting without a subsequent caustictreatment,v while in the second run it was subjected to bothdeasphalting and caustic treatment. The residuum was diluted withpropane in the proportion of ten parts of propane to one part ofresiduum and asphalt precipitated therefrom at a temperature of 163 F.The remaining solution was then treated with an additional quantity ofpropane, about three or four volumes, to remove the resinousconstituents at a temperature of around F.

The same procedure Was followed in the run in which caustic treatmentwas applied, the caustic treatment being applied before recipitation ofthe resinous constituents. A relatively strong caustic solution was usedin this instance, consisting of 25% by'weight of caustic. The solutionwas used in the proportion of about 2.2

volumes to l volume of residuum.

The oil obtained by deasphalting and caustic treatment possessed thedesiredgreen cast; also, as indicated, the treatment with causticeiectively reduced the neutralization number.

In another example a Manvel residuum having the following tests:

was subjected to treatment in accordance with our invention. Thisinvolved first subjecting the residuum to deasphalting and deresinatingby treatment with a volume of propane equal to twelve times the Volumeof the residuum. This was carried out inl a countercurrent treatingtower, the temperature at the top of the tower being 164 F. and thetemperatureat the bottom being 163 F. In the course of this treatmentthe asphaltic and resinous materials were precipitated and removedsimultaneously.

'Ihe propane solution of deasphalted and deresinated oil was drawn oilcontinuously from the top of the tower and then subjected to continuoustreatment with approximately 77% by volume on the basis of charge oil ofa 0.26% by weight aqueous solution of caustic soda, the eX- tractionwith caustic soda solution being carried out at a temperature of F. Thecaustic treated oil was then separated from the propane. It had thedesired green cast and on testing was found to have the following tests:

Gravity, A. P. I 20.8 Flash 500 Fire 580 Vis/210 157 Color, Tag Rob 1/8Pour F 30 Garbo-n residue, percent 1.84 Neutralization number 0.07

Obviously, many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should loeimposed as are indicated in the appended claims.

We claim:

1. The method of preparing lubricating oil suitable as cylinder stock,substantially free from asphaltic and acidic constituents and having adesirable green cast, from reduced naphthene base crude comprisingdiluting the oil with a liquefied normally gaseous petroleum hydrocar-Vbon solvent, deasphalting the oil in the presence of said liqueedsolvent and treating the oil without intervening treatment withinorganicacid with a large excess of dilute caustic soda solution in thepresence of said liquefied solvent to remove the acidic constituents ofthe oil without substantially aecting adversely the constituents of theoil imparting the desired green cas-t.

2. The method of preparing lubricating oil suitable as cylinder stock,substantially free from asphaltic and acidic constituents and having adesirable green cast, from reduced naphthene base crude comprisingdiluting the oil with a liquefied normally gaseous' petroleumhydrocarbon solvent, deasphalting the oil in the presence of saidliquefied solvent and treating the oil with about 0.2% to 0.5% causticsodav solution in amount about 25 to `200% by volume inexcess of thatrequired to neutralize the organic acidity and in the presence of saidliqueed solvent to remove the acidic constituents of the oil Withoutadversely affecting the constituents of the oil imparting the desiredgreen cast.

3. In the countercurrent treatment of lubricating oil stock derived fromnaphthene base crude petroleum with caustic soda solutionto removeorganic acidity, the steps comprising diluting the oil with a liqueednormally gaseousv petroleum hydrocarbon solvent, continuouslyintroducing the diluted mixture near the bottom of a packed tower Vlledsubstantially with dilute mixture maintained under pressure sufcient to`maintain the diluent liquefied, continuously introducingl -ing ofsodium, potassium and' ammonium, the

steps comprising diluting` the oil with a liquefied normally gaseouspetroleum hydrocarbon, charging the dilute oil near the bottom of apacked tower, charging the reagent near the top of said tower,maintaining the diluted oil under pressure suiiicient to maintain thediluent liquefied, maintaining the interface level between the reagentand the oil within the tower at a point intermediate the points of oiland reagent introduction to the tower, thereby causing the oil to flowthrough a substantial body of reagent within the lower portion of thetower, withdrawing used reagent and sludge from the bottom of the tower,and withdrawing the treated dilute oil from the top of the tower.

5. The method of preparing lubricating oil, suitable as cylinder stock,substantially free of asphaltic and acidic constituents and having adesirable green cast, from reduced naphthene base crude, comprisingmixing the oil with a liqueiied normally gaseous petroleum hydrocarbonsolvent in proportion sufficient to precipitate substantially all theasphalt, removing the asphalt in the presence of the liquelied solventand treating the deasphalted oil, without subjecting it to anintervening treatment with inorganic acid and while still mixed with theliquefied solvent, with a I large excess of a dilute solution of ahydroxide selected from the hydroxides of the alkali group consisting ofsodium, potassium and yammonium to remove the organic acidicconstituents of the oil Without substantially affecting,adversely theconstituents imparting said green cast to the oil.

6. The method according to claim 5 in which the vliquefied hydrocarboncomprises mainly propane.

7. 'I'he method of preparing lubricating oil, suitable as cylinderstock, substantially free from asphaltic and acidic constituents andhaving a desirable green cast, from reduced naphthene base crude,comprising mixing the oil with a liqueed normally gaseous petroleumhydrocarbon, deasphalting the oil in the precence of said liquefiedsolvent and treating .the oil, without an intervening treatment withinorganic acid, with a large excess of dilute caustic alkali solution inthe presence ofsaid liqueed solvent to remove theorganic acidicconstituents of the oil1without substantially aiecting adversely theconstituents imparting the desired green cast.

8. The method according to claim 5 in which the resulting deacidied oilis treated with further liquefied solvent to remove resinousconstituents.

9. In the method of preparing naphthene base cylinder stock of desirablegreen cast from reduced naphthene base crude and not requiring treatmentwith inorganic acid, the combination of steps which comprises dilutingthe residuum with a liquefied normally gaseous petroleum hydrocarboncapable of precipitating asphaltic constituents therefrom, subjectingthe diluted mixture to settling to remove asphaltic constituents,treating the diluted mixture with a dilute hydroxide solution selectedfrom the hydroxides of the alkali group consisting of sodirun, potassiumand ammonium, said hydroxide solution being in large excess of theamount required to neutralize the organic acidity of the oil undergoingtreatment, such that organic acidic constituents of the oil are removedWithout substantially aiecting adversely the constituents imparting saidgreen cast to the oil, and maintaining the dilute mixture during saiddeasphalting and alkali treating steps under pressure suficenttomaintain the diluent liquefied.'y

10. In the method of preparing naphthene base cylinder stock ofdesirable green cast from reduced naphthene base crude, the combinationof steps which comprises diluting the reduced crude with a liqueednormally gaseous petroleum hydrocarbon, removing asphaltic constituentsfrom the reduced crude in the presence of the liquefied diluent, andtreating Vthe reduced crude inthe presence of the liquefied diluent witha dilute hydroxide solution selected from the hydroxides of the alkalivgroup consisting of sodium, potassium and ammonium, said solutionamounting to about 25`to 200% by'volume in excess of that required toneutralize the organic acidity of the oil and having an alkalinityapproximately equivalent to a caustic soda solution containing around0.2 to 0.5% by Weight of caustic soda. y

1l. The method of preparing lubricating oil,

suitable as cylinder stock, substantially free from asphaltic and acidicconstituents and having a desirable green cast, from reduced naphthenebase crude, comprising mixing the oil with a liquefied normally gaseouspetroleum hydrocarbon solvent, maintaining the diluted mixture-underpressure suflicient to maintain the diluent liquefied, deasphalting themixture of oil and liquefied diluent, and treating the dasphaltedmixture of oil and liquefied diluent with a caustic alkali solutionamounting to about 25 to 200% by volume in excess of that required toneutralize the organic acidity of the oil, said solution having aconcentration of around 0.2 to 0.5% by Weight of caustic soda and suchthat organic acidic constituents of the oil are removed Withoutsubstantially affecting adversely the constituents imparting said greencast to the oil.

CHARLES T. ANNE.

HERMAN I. WILSON.

WILLIAM C. PATTERSON,

